Only smallest size (400×267 pixels) are free with an attribution required. Option to purchase super high resolution (bigger size) files for use in print or graphic design. No registration required for the free download, corporate use is OK, and optional member registration gives access to lightboxes and email-to-a-friend features.

Everystockphoto.com is a license-specific photo search engine who has indexed millions of freely licensed photos, from many sources (Flickr, morgueFile, freerangestock, stock.xchng, etc) and present them in an integrated search.

Thanks for the nice list. I also wanted to suggest a good site for free stock photos: http://www.kozzi.com. People are welcome to used their photos and images. Also, they add new images everyday which is a great thing and their images are easy to download. :) Check out their cool photos. :) ^^,)

Hi, very informative article.
Please also check out https://www.goodfreephotos.com for thousands of unique public domain photos, all high-resolution and free to use for any purpose.We specialize in photos by location as we document cities, national parks, state parks, national landmarks, and more. We update with 20+ photos each week. Appreciate it if you could add us to your list of sites.